


Cantis

by hotfruits



Series: Harry Potter AU [5]
Category: Criminal Minds
Genre: Alternate Universe - Fantasy, Alternate Universe - Harry Potter Setting, M/M, Past Child Abuse, Past Rape/Non-con, Past Torture, Polyjuice Potion
Language: English
Status: Completed
Published: 2015-08-28
Updated: 2015-08-28
Packaged: 2018-04-17 15:59:55
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,570
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4672679
Author URL: https://archiveofourown.org/users/hotfruits/pseuds/hotfruits
Summary: <blockquote class="userstuff">
              <p>Over the course of a month, Derek and Spencer work on a Polyjuice Potion, allowing them to grow in knowledge, and in their relationship.</p>
            </blockquote>





	Cantis

**Author's Note:**

> Thank you Harry Potter Wiki, for having detailed descriptions and instructions for nerds like me ♥

Derek cursed as he walked into a spider’s web, hands flailing to knock away the silky string. From behind him, he heard a muffled laugh, and turned towards his boyfriend with an accusatory glare. “Keep laughing and I’ll make you walk through the spider’s webs,” Derek threatened with a grumble, to which Spencer smiled sweetly at. “You’re lucky I like you,” Derek said pointedly, before turning back around and resuming their walk through the forbidden forest.

For the past few weeks, Derek had been stressed; after much prompting from Spencer, he finally confided in the other what was going on. Advanced Potions was proving to be much harder than he had anticipated, and if he was going to be an Auror like his father, he needed a perfect score on his N.E.W.T.s next year. This inspired Spencer to become his tutor, and the reason he was out after curfew – on a full moon – in the forbidden forest. “Are you sure we couldn’t use the Fluxweed in the greenhouses?” Derek asked again, despite knowing the answer wouldn’t change.

“Technically, we’re not supposed to be making this potion until the end of the year,” Spencer began to repeat himself, “And if sixteen scruples of Fluxweed go missing from the greenhouses, they’ll know it’s being used to make a Polyjuice Potion,” Derek stopped and turned around, giving Spencer a hand over some tangled roots, “Plus, isn’t this kind of fun?”

“Oh yeah,” Derek gripped Spencer’s hand as he rolled his eyes, “Being in the forbidden forest on a full moon. My favorite.”

“Don’t be an ass,” Spencer gave his shoulder a little bump, bringing a slight smile to his face, “And it’s not like we’ll run into any werewolves or vampires. Maybe Centaurs, but as long as you’re respectful, they won’t hurt us.”

“What about giant spiders?”

Spencer shook his head, “We’d have to go much deeper into the forest to see any Acromantula. Did you know their venom can be sold for one hundred galleons?”

“Why do you know that?” Derek asked incredulously, to which Spencer raised a single brow at, “Right, I forgot for a second that I’m dating a huge fucking nerd.”

Spencer proudly beamed at him, before saying, “Female Acromantula can lay up to one hundred eggs, which are roughly the size of beach balls. They typically hatch in six to eight weeks, and are a Class A Non-Tradeable Material.”

“Which means…?”

“They’re super dangerous,” Spencer said excitedly, and Derek resisted the urge to smack him, “The only other Class A items are dragon and chimera eggs,” noticing Derek’s confusion, Spencer added, “Chimera’s have the head of a lion, the body of a goat, and the tail of a dragon.”

“They sound badass,” Derek said, both terrified and impressed.

Spencer nodded, opening his mouth to continue when he suddenly stopped. Derek looked at him in concern, before following his line of sight; a thick bushel of Fluxweed was glowing in the moonlight, enough to make several batches of Polyjuice Potion. Discovering the plant isn’t what made Spencer freeze, though, and once Derek registered what was happening, he quietly swore to himself.

“We’ll have to stun them,” Spencer whispered, eyes trained on the Cornish Pixies that danced above the Fluxweed they desperately needed. Derek nodded his understanding, and together, the two began to stun the little demons. Thankfully, they were able to remain unscathed, due to their speed and the element of surprise.

“Quick!” Spencer exclaimed, the two of them rushing forward and plucking scruples of Fluxweed. Once they had all sixteen, they quickly ran from the scene, tripping over roots and giggling from excitement. After a few moments, they began to slow down, chests heaving as they took in large gulps of air.

“That was,” Derek coughed, but still smiled, “Oh my god, that was crazy!”

“We got it!” Spencer grinned, waving the plant in the air. “And once the lacewings finish stewing in a week, we can began step one!”

“Ugh, you’re so geeky,” Derek groaned, bringing Spencer into his arms and resting his sweaty forehead against the others.

“Shouldn’t we start heading back?” Spencer asked quietly, while bringing his arms around Derek’s shoulders.

Derek hummed, his nose brushing against Spencer’s as he moved his lips towards the others, “Rule breaking. A full moon. It’s fun, right?”

Spencer grinned, closing the distance between them in a heated kiss.

 

***

“After you’ve added the knotgrass,” Derek looked up from his cauldron as Spencer spoke, waiting for the next set of directions, “You have to stir it three times, clockwise, and then wave your wand over it.”

“And then?” Derek asked as he began to stir the potion.

“Let it brew for eighty minutes,” Spencer smiled, giving Derek a soft peck on the cheek. “You’re a lot better at potions than you give yourself credit for.”

Derek turned his head as he set down his wand, leaning his forehead against Spencer’s, “Or maybe I am that bad, but you just see the best in me because you _like me_ ,” Derek said with a teasing grin.

“Blasphemy,” Spencer whispered, watching as Derek’s mischievous eyes softened, along with his silly grin. Their lips were only an inch shy of meeting, and yet neither seemed interested in closing the distance; they simply enjoyed the moment, warm and content in each others presence.

“Hey, pretty boy?” Derek asked several minutes later, his eyes blinking open as he cleared his throat. “Can I ask you something?”

“Of course,” Spencer replied, allowing Derek to pull away from their moment and sit back, his hands supporting most of his weight. Spencer followed suit, crossing his legs and resting his elbows on his knees.

“What do you want to do, after Hogwarts?”

“Like, career-wise?” Spencer asked, in order to clarify Derek’s question.

Derek shrugged, “Like, anything-wise.”

“Um,” Spencer ran a hand through his hair, “I don’t know. It changes.”

Derek smiled, encouraging him.

“Sometimes I think about becoming a professor, but then other times I think about becoming a healer…” Spencer paused, twisting his fingers together, “Or maybe an auror.”

“Yeah?”

Spencer shrugged, unsure of how to respond.

“Hey,” Derek said quietly, leaning forward and into Spencer’s space once more, “Most people may think you’re just a smarty-pants Ravenclaw, but I know the truth.”

“And what’s that?”

“You’ve got the heart of a lion, pretty boy,” Derek replied, giving Spencer a chaste kiss, “And you’d be an amazing auror.”

 

***

Derek grimaced as he watched his potion brew, the thick, black goo bubbling inside the copper cauldron. “That’s so gross,” he mumbled, fingers combing through Spencer’s locks, who was reading a book about flesh-eating trees from around the world.

“Did you know that some forms of Venomous Tentacula can fire spikey, spore-like balls at their targets?” Spencer asked, looking up at Derek over the top of the book.

“I don’t know anyone but you and the Herbology professor who know that,” Derek chuckled, giving a particularly bouncy curl a tug. Spencer yelped, swatting his hand away.

“How long it does it have to brew again?”

“Since your cauldron is copper, just eighteen hours,” Spencer replied, eyes back on the text in front of him.

“ _Just_ eighteen hours,” Derek rolled his eyes, wrapping his finger around a strand of hair and curling it against Spencer’s scalp. “What inspired you to be an auror?”

“What?”

“What inspir-”

“No,” Spencer shook his head, placing the book next to the cauldron and sitting up, eyes on Derek. “Sorry, I heard the question, you just asked it so suddenly.”

“It occurred to me suddenly,” Derek shrugged, smiling. “So,” he gestured towards Spencer, “What inspired you?”

“What inspired you?” Spencer said instead, turning the question back onto Derek.

“My dad,” Derek answered, “He was a great auror.”

“That’s not the only reason though, is it?” Spencer continued to question, deflecting the attention away from himself.

Derek became quiet, staring at Spencer with a thoughtful expression. Spencer didn’t let his eyes waiver, and kept his locked on Derek’s. “If I tell you…” Derek began, slowly, “Will you tell me?”

Spencer nodded.

Derek took a deep breath, and then let it out in a heavy sigh, “After my dad died, my family and I moved to Puddlemere. That’s where I met Carl,” he looked down at his lap, “He was a retired Quidditch player…”

Spencer grabbed Derek’s hand, giving it a squeeze.

“When he offered to train me, my mom was so happy. She felt I needed a male role model, plus something to keep me active and out of trouble. At first, it was great,” his voice cracked with emotion, but his eyes remained dry, “But then Carl started…it wasn’t anything bad at first, at least not illegal. Hugging me too long, rubbing my back, things like that.”

“Oh, Derek,” Spencer brought Derek’s hand to his mouth, kissing the calloused muscles. “I’m so sorry.”

“It was Penelope who convinced me to report him,” Derek smiled slightly, “And when the aurors took him away, I knew that’s what I wanted to do. I wanted to stop the bad guys; just like them, just like my dad…”

Spencer couldn’t help himself, as he lunged forward and enveloped Derek in a tight hug. Derek returned the embrace with equaled fervor, burying his face against Spencer’s pale neck. They stayed like that for several moments, finding comfort in one another’s arms.

Eventually they broke apart, but still remained close in one another’s space. “You’ve noticed the scars on my wrists and back, right?” Spencer asked, and when Derek nodded, he continued, “The thing is, I’m a muggleborn. And my father was a lawyer and my mother a professor at Oxford, until she got sick.”

Derek opened his mouth to ask a question, but Spencer interrupted him, saying in a rush, “I shouldn’t say got sick, because she was always sick. She has paranoid schizophrenia…” Spencer paused, rubbing at the marks on his wrists, “And I was her wizard child.”

“How did she handle it?” Derek asked, although he could imagine how problematic that could be.

“Not well,” Spencer chuckled sarcastically, shaking his head, “My powers would randomly spike, as they do with children…exploding light bulbs, things moving across the room, the usual. She thought I was possessed by a demon.”

“Not a good thing for a schizophrenic to think,” Derek mumbled, as the skin around Spencer’s wrists began to turn pink. He quickly grabbed his hands, interlacing their fingers together.

Spencer sighed, “No, it wasn’t. She found a priest, Father Hankel, who agreed to “lift the demon’s spirit from my body",” he said, using air quotes.

Derek paused, and then asked, “Wait, an exorcism? This guy gave you a fucking exorcism?”

“Tried to,” Spencer corrected, “When I got home from school, he tied me to my bed and shouted prayers at me, while flinging holy water from a palm branch. When that didn’t work,” Spencer squeezed Derek’s hands, who squeezed back, reassuringly, “He filled the bath tub with water and blessed it, and then submerged me under the water. And of course my abilities starting acting up, because I was stressed and afraid for my life.”

Spencer stopped, and took a deep breath, and another. “After I blew out the lights in the bathroom, he dragged me back into my bedroom and starting beating me with his belt. It…it was so,” Spencer faltered, hands shaking within Derek’s grasp, “I guess I was so screaming so loud, the neighbors heard and called the police.”

“Please tell me that bastard is rotting away in prison.”

“When the police showed up, they took Father Hankel and my mother away,” Spencer said, ignoring Derek’s previous request, “But I didn’t want them to take her, because I knew it wasn’t her fault. So, I ended up…flinging the officer across the room.”

Derek’s eyes widened.

“That surge of power caught the attention of the aurors, specifically Dave and Gideon.”

“Dave and Gideon? As in Professor Rossi and Headmaster Gideon?” Derek questioned.

Spencer nodded, “Once they saw what happened, they knew I wasn’t a dark wizard causing problems. They were worried, though, about a wizard being placed in the muggle foster care system.”

“Don’t expose the wizarding world,” Derek said, repeating the old mantra they were taught as first years.

“Exactly. Which is why Dave used a variety of charms to convince a judge I was his nephew, since my father was no longer around and I couldn’t be in foster care. The judge granted him full custody, and I’ve been living with Dave ever since.”

“And that’s why,” Derek said quietly, with a small smile, “You were saved by an auror, just like me, and now you want to give back.”

Spencer nodded, easing a hand out of Derek’s grasp, in order to wipe away the tears that had been rolling down his cheeks. “Father Hankel died of a drug overdose, by the way,” he said, sniffling as emotions long repressed caught up with him, “A year ago, after he was released from Broadmoor Hospital into his father’s care.”

Derek kept quiet, and simply hugged Spencer once more, the bubbling potion forgotten for now.

 

***

“So, this is what you’ve been doing for the past month?” Emily asked, looking at the sluggish drink that had been placed in her hand. “Making Polyjuice Potion?”

“Yup!” Derek exclaimed, his arm wrapped tight around Spencer’s waist, who was holding both of their glasses.

“Man, I just thought you guys were fucking a bunch,” Emily stated, cracking a smile when Spencer coughed uncomfortably. “And here you are, being big nerds instead.”

“Oh, you wound me so,” Derek said mockingly, before grabbing his drink from Spencer’s hand and raising it into the air, “A toast! To my beautiful boyfriend, for helping me create this potion,” Derek paused, kissing Spencer’s cheek, “And to my new bestie Emily, who hates the word bestie. Bestie.”

“Ugh,” Emily groaned, clinking her glass against the others.

Together, all three choked down their portion of the potion. As soon as she finished, Emily dropped her glass and rushed into the bathroom, heaving into the toilet. Derek and Spencer quickly followed suit, gagging against the foul taste as their bodies shifted; bones cracked beneath their skin, hair grew rapidly from their heads, and their school robes quickly became too long and too tight.

“Oh god,” Spencer moaned, his voice several octaves higher. “Emily, Derek?”

“I’m okay,” Derek muttered, his now bubbly voice echoing inside the stall.

“I hate you both,” Emily replied, with a deep, rumbly voice.

One by one, the three exited their stalls and faced each other, taking in their temporary appearance. “This is crazy,” Spencer said, watching Derek’s expressions on Penelope’s usually happy face, and Emily’s scowl plastered across Aaron Hotchner’s.

“No kidding,” Derek replied, gesturing towards Spencer’s now tiny frame, “Why did you pick Ashley Seaver, by the way?”

“I tutor her on Wednesday’s, so it was easy to pluck a hair while she was distracted,” Spencer shrugged, arms crossed over his chest. “Can I just say that having breasts is a very odd feeling?”

“Trying having a dick,” Emily retorted, trying to adjust herself in her skirt.

“I’m happy!” Derek giggled as he shimmied, ignoring Spencer and Emily’s eye rolls.

“So, what’s the plan for the next hour?” Emily asked, arms crossed over her flat chest, “Shaving my legs? Watching Derek’s tits bounce around?”

Spencer shrugged, smiling.

**Author's Note:**

> Check out Penelope's Character Profile on my writing tumblr [here](http://hotfruits.tumblr.com).


End file.
